What could cause a fuse to completely melt like in these pictures? I've occasionally noticed an electrical burning smell while driving my 93 CTD over the last week or two but today it was especially noticeable, so I stopped and opened up the fuse panel to take a look. Turns out all of the plastic of fuse #4 was completely melted but the metal part of the fuse was completely intact and functional. Fuse #4 controls the marker lights, taillights, instrument panel lights, and horn, but these were all working fine. I pulled as much of what was left of the fuse out so it wouldn't catch fire while I was at work. What in the world would cause something like this?

It's really strange because the fuse itself didn't blow, so it doesn't seem like there was a short to ground downstream of the fuse. I've pulled the wires off the back of the fuse and wired them temporarilty to 12v, all the lights and everything work fine and I measure about 4 amps draw with all the lights on.

Anyone seen anything like this?

 

maybe the previous owner installed a larger fuse than should have been there?

 

That looks like a bad crimped connection to the female terminal where the fuse plugs into.
It got hot and started melting the holder.
Maybe..
Jim

 

I have been smelling a burning smell in my cab the last couple of days as well. I figured it was from the oil I had spilled on my exhaust from changing the tranny fluid, but after looking at this post, I pulled the fuse box and sure enough, same problem. Even the same fuse. I know I had the correct fuse, as I have been having problems with my fuse blowing when I have the tail gate down (It has lights at the bottom of it) and my running lights on. The 1st good bump and pop, there goes my fuse. Not sure of the solution, but interested in what the folks here with more knowledge than I might be thinking.

Thanks!

Jeff

 

My thought is that there could be a bad ground somewhere.

 

jeff, i say cut the wires that lead to the tailgate lights and cap them that's the simple solution!

 

Mr. Lane nailed it, loose connection, wich builds heat wich builds resistance...and on and on etc. etc. Also it looks like it`s the fuse for the exterior lamps, might want to make sure you don`t have too much (added on) stuff pulling on the ckt.

 

I am gonna offer my diagnosis to the melting fuse scenario.

I was smart and bought a big assortment of fuses, in a sectioned plastic box, enough to last a lifetime, for five bucks.

I started using them in various applications.

They will not shoot, no matter what you put them through.

However, they will get extremely hot and drip like candle-wax.

I have decided that the metal in them is of a very poor conductive material, causing an electrical bottleneck in the little "shootable" section of the fuse, thereby building up heat and melting the plastic.

After having numerous fuse meltdowns, I started replacing the el-cheapo fuses with BUSS brand fuses.

By simply replacing the melting fuses with BUSS fuses, I have had no more melt-downs.

I had an el-cheapo 40-amp fuse in the circuit that handles something like a hundred trailer markers; it melted in less than thirty miles.

I replaced it with a BUSS and have over a thousand miles with no sign of melting.

 

This sounds like a good plan. After doing some more investigating on my truck, and the fact that my fuses were blowing 1st, and now started melting, I think BearKiller has it right. I started using an assortment of cheap fuses when this problem occurred. I also noticed I may have had a wire touching the hot brass bar feeding that line of fuses, thus bypassing the fuse and causing alot of heat to melt it. Either way, I think the fuse should have blown.

Good info on here. Thanks to everyone for the help!